Internal combustion engines may combust a mixture of air and fuel within one or more combustion chambers to produce a mechanical output. During the combustion, various exhaust gases are produced and expelled to the atmosphere. In some instances, a portion of the exhaust gas may be recirculated back into the engine cylinders (via an exhaust gas recirculation system). In a gasoline engine, this inert exhaust may displace an amount of combustible mixture in the cylinder resulting in increased engine efficiency. In a diesel engine, the exhaust gas may replace some of the excess oxygen in the pre-combustion mixture. In either instance, the recirculated exhaust may reduce the combustion temperature in the cylinder and/or reduce the creation of certain gaseous byproducts.